If it is uncertain whether such therapy will be tolerated by the patient, esmolol may be cautiously administered since its very short half-life permits a therapeutic trial to be performed at reduced risk (see ‘Acute control with beta blockers’ above).

In patients who do not adequately respond to initial therapy with either an intravenous beta blocker or intravenous calcium channel blocker, we suggest the addition of intravenous digoxin as the second drug in combination therapy (Grade 2C). (See ‘Digoxin’ above.) Some patients have a greater degree of rate control with a beta blocker than with a calcium channel blocker, and vice versa. Thus, in patients who have an inadequate response to one of these drugs, switching to a drug from the other class is an alternative to adding digoxin.If rate control is achieved, we try to use the second drug as a single agent and to avoid using beta blockers and calcium channel blockers as combination therapy for rate control. However, in selected patients who do not have hypotension or significant left ventricular dysfunction, these classes may be used together, and in some cases all three agents (ie, a beta blocker, a calcium channel blocker, and digoxin) may be necessary to achieve adequate rate control.

In patients who do not respond to or are intolerant of intravenous calcium channel blockers, beta blockers, and/or digoxin, we suggest intravenous amiodarone for acute control of the ventricular rate (Grade 2C). (See ‘Amiodarone’ above.) In such patients, the use of amiodarone for rate control is a short-term strategy (eg, hours to days).

Amiodarone — Amiodarone is commonly used to maintain sinus rhythm in AF patients in whom a rhythm control strategy is chosen. However, amiodarone can also slow the ventricular rate in patients who remain in AF. In one study, for example, intravenous amiodarone (7 mg/kg), flecainide, or placebo was given to 98 patients with recent onset AF (0.5 to 72 hours) [42]. Even when AF did not revert to sinus rhythm, amiodarone promptly slowed the ventricular rate during the eight hour observation period (figure 4). In addition, in critically ill patients, amiodarone may be less likely to cause systemic hypotension than intravenous diltiazem [43].http://www.uptodate.com/contents/control-of-ventricular-rate-in-atrial-fibrillation-pharmacologic-therapyatrial fibT